Following [1]}, our optimization target is
\(\begin{split}E(\theta _f, \theta _p, \theta _d) &= \sum _{i=1}^{N_s}L_s(H_p(H_f (x_i; \: \theta _f); \: \theta _p), \: y_i) \\ & - \lambda \sum _{j=1}^{N_2} L_{d}(H_d(H_f (x_j; \: \theta _f); \: \theta _d), \: d_j) = \\&= \sum _{i = 1}^{N_s} L_s \left(\hat{y}_i ,\: y_i \right) \: - \: \lambda \sum _{j = 1}^{N_2} L_d (\hat{d}_j,\: d_j )\end{split} \\(\hat{\theta }_f, \hat{\theta }_p) & = \operatornamewithlimits{arg\,min}_{\theta _f, \theta _p} E(\theta _f, \theta _p, \theta _d), \\\hat{\theta }_d & = \operatornamewithlimits{arg\,max}_{\theta _d} E(\theta _f, \theta _p, \theta _d),\) 
